Detection of leaks in systems containing fluids under pressure is often accomplished by causing visible fluorescence of fluorescent dyes that are added to the fluid in the system. Such systems may be, for example, refrigeration systems where the fluid under pressure is a refrigerant and leakage results in the fluid becoming an invisible gas upon escape. The invisibility of leaked fluid can impair detection of the leak. Addition of a fluorescent dye to the refrigerant allows easier detection of leaks by illuminating possible leakage points with radiation that causes the fluorescent dye to visibly fluoresce at the site of the leak.
Leak detection by means of use of a fluorescent dye is also used in systems other than refrigeration systems, such as automotive cooling systems and in engines having a lubricant that is under pressure.
There are many inspection lamps currently available for the purpose of illuminating potential leak sites with radiation cause visible fluorescence of fluorescent dyes. It is desirable to minimize the size, weight, cost, heat production and power consumption of such inspection lamps while having adequate output from such lamps at wavelengths suitable for causing visible fluorescence of dyes used for leak detection.
Light emitting diodes (LEDs) are used as a source of light for such inspection lamps. LEDs are more efficient at producing desired wavelengths than other light sources used in such inspection lamps. LEDs are also relatively small and produce relatively little heat. Existing LED inspection lamps have had 4 LEDs in an attempt to produce sufficient intensity at a usable distance to make a fluorescent dye fluoresce. For some situations this defeats the purpose of the LED source as additional power must be consumed and the size of the lamp is increased accordingly.
In traditional inspection lamps a broadband light source is utilized, such as an incandescent or halogen bulb. This can have an advantage over LED sources as these sources have a greater radiation output, and they emit radiation over a broad spectrum that can cause a variety of fluorescent dyes to fluoresce. LEDs have a tendency to produce light only in a narrow range of wavelengths.
However, traditional lamps suffer from a number of drawbacks. The broadband light source produces mostly radiation that is not used for detection of any fluorescent dye that has frequent use for leak detection. Also, some of the radiation may be at wavelengths normally emitted by the fluorescent materials to be detected. Filters are typically used to remove such wavelengths from the output of the inspection lamp so that light from the inspection lamp does not mask fluorescence of the fluorescent material to be detected. Radiation absorbed or reflected by filters results in heat, often necessitating means to dissipate this heat.
Alternatively, inspection lamps have been produced using electric discharge light sources since such light sources are often more efficient than incandescent light sources at producing wavelengths suitable for causing visible fluorescence of materials used for leak detection. Such inspection lamps have their own disadvantages such as the cost of the special discharge light sources having sufficient intensity, the added cost of electrical components required for operation of such light sources, a requirement for some such light sources to spend time wanning up to a required elevated operating temperature in order to properly function, and the tendency of many discharge light sources to specialize in production of wavelengths not effectively utilized by all popular fluorescent dyes. There is a need to derive the full benefit of utilizing LED light sources in inspection lamps. There is also a need to retain some of the benefits of traditional light sources. It is an object of the invention to address these or other issues associated with LED inspection lamps.